openlayers/src/ol/render/Feature.js

/**
 * @module ol/render/Feature
 */
import {extend} from '../array.js';
import {createOrUpdateFromCoordinate, createOrUpdateFromFlatCoordinates, getCenter, getHeight} from '../extent.js';
import GeometryType from '../geom/GeometryType.js';
import {linearRingss as linearRingssCenter} from '../geom/flat/center.js';
import {getInteriorPointOfArray, getInteriorPointsOfMultiArray} from '../geom/flat/interiorpoint.js';
import {interpolatePoint} from '../geom/flat/interpolate.js';
import {get as getProjection} from '../proj.js';
import {transform2D} from '../geom/flat/transform.js';
import {create as createTransform, compose as composeTransform} from '../transform.js';


/**
 * @type {import("../transform.js").Transform}
 */
const tmpTransform = createTransform();


/**
 * Lightweight, read-only, {@link module:ol/Feature~Feature} and {@link module:ol/geom/Geometry~Geometry} like
 * structure, optimized for vector tile rendering and styling. Geometry access
 * through the API is limited to getting the type and extent of the geometry.
 */
class RenderFeature {
  /**
   * @param {GeometryType} type Geometry type.
   * @param {Array<number>} flatCoordinates Flat coordinates. These always need
   *     to be right-handed for polygons.
   * @param {Array<number>|Array<Array<number>>} ends Ends or Endss.
   * @param {Object<string, *>} properties Properties.
   * @param {number|string|undefined} id Feature id.
   */
  constructor(type, flatCoordinates, ends, properties, id) {
    /**
     * @private
     * @type {import("../extent.js").Extent|undefined}
     */
    this.extent_;

    /**
     * @private
     * @type {number|string|undefined}
     */
    this.id_ = id;

    /**
     * @private
     * @type {GeometryType}
     */
    this.type_ = type;

    /**
     * @private
     * @type {Array<number>}
     */
    this.flatCoordinates_ = flatCoordinates;

    /**
     * @private
     * @type {Array<number>}
     */
    this.flatInteriorPoints_ = null;

    /**
     * @private
     * @type {Array<number>}
     */
    this.flatMidpoints_ = null;

    /**
     * @private
     * @type {Array<number>|Array<Array<number>>}
     */
    this.ends_ = ends;

    /**
     * @private
     * @type {Object<string, *>}
     */
    this.properties_ = properties;

  }

  /**
   * Get a feature property by its key.
   * @param {string} key Key
   * @return {*} Value for the requested key.
   * @api
   */
  get(key) {
    return this.properties_[key];
  }

  /**
   * Get the extent of this feature's geometry.
   * @return {import("../extent.js").Extent} Extent.
   * @api
   */
  getExtent() {
    if (!this.extent_) {
      this.extent_ = this.type_ === GeometryType.POINT ?
        createOrUpdateFromCoordinate(this.flatCoordinates_) :
        createOrUpdateFromFlatCoordinates(
          this.flatCoordinates_, 0, this.flatCoordinates_.length, 2);

    }
    return this.extent_;
  }

  /**
   * @return {Array<number>} Flat interior points.
   */
  getFlatInteriorPoint() {
    if (!this.flatInteriorPoints_) {
      const flatCenter = getCenter(this.getExtent());
      this.flatInteriorPoints_ = getInteriorPointOfArray(
        this.flatCoordinates_, 0, /** @type {Array<number>} */ (this.ends_), 2, flatCenter, 0);
    }
    return this.flatInteriorPoints_;
  }

  /**
   * @return {Array<number>} Flat interior points.
   */
  getFlatInteriorPoints() {
    if (!this.flatInteriorPoints_) {
      const flatCenters = linearRingssCenter(
        this.flatCoordinates_, 0, /** @type {Array<Array<number>>} */ (this.ends_), 2);
      this.flatInteriorPoints_ = getInteriorPointsOfMultiArray(
        this.flatCoordinates_, 0, /** @type {Array<Array<number>>} */ (this.ends_), 2, flatCenters);
    }
    return this.flatInteriorPoints_;
  }

  /**
   * @return {Array<number>} Flat midpoint.
   */
  getFlatMidpoint() {
    if (!this.flatMidpoints_) {
      this.flatMidpoints_ = interpolatePoint(
        this.flatCoordinates_, 0, this.flatCoordinates_.length, 2, 0.5);
    }
    return this.flatMidpoints_;
  }

  /**
   * @return {Array<number>} Flat midpoints.
   */
  getFlatMidpoints() {
    if (!this.flatMidpoints_) {
      this.flatMidpoints_ = [];
      const flatCoordinates = this.flatCoordinates_;
      let offset = 0;
      const ends = /** @type {Array<number>} */ (this.ends_);
      for (let i = 0, ii = ends.length; i < ii; ++i) {
        const end = ends[i];
        const midpoint = interpolatePoint(
          flatCoordinates, offset, end, 2, 0.5);
        extend(this.flatMidpoints_, midpoint);
        offset = end;
      }
    }
    return this.flatMidpoints_;
  }

  /**
   * Get the feature identifier.  This is a stable identifier for the feature and
   * is set when reading data from a remote source.
   * @return {number|string|undefined} Id.
   * @api
   */
  getId() {
    return this.id_;
  }

  /**
   * @return {Array<number>} Flat coordinates.
   */
  getOrientedFlatCoordinates() {
    return this.flatCoordinates_;
  }

  /**
   * For API compatibility with {@link module:ol/Feature~Feature}, this method is useful when
   * determining the geometry type in style function (see {@link #getType}).
   * @return {RenderFeature} Feature.
   * @api
   */
  getGeometry() {
    return this;
  }

  /**
   * @param {number} squaredTolerance Squared tolerance.
   * @return {RenderFeature} Simplified geometry.
   */
  getSimplifiedGeometry(squaredTolerance) {
    return this;
  }

  /**
   * Get the feature properties.
   * @return {Object<string, *>} Feature properties.
   * @api
   */
  getProperties() {
    return this.properties_;
  }

  /**
   * @return {number} Stride.
   */
  getStride() {
    return 2;
  }

  /**
   * @return {undefined}
   */
  getStyleFunction() {
    return undefined;
  }

  /**
   * Get the type of this feature's geometry.
   * @return {GeometryType} Geometry type.
   * @api
   */
  getType() {
    return this.type_;
  }

  /**
   * Transform geometry coordinates from tile pixel space to projected.
   * The SRS of the source and destination are expected to be the same.
   *
   * @param {import("../proj.js").ProjectionLike} source The current projection
   * @param {import("../proj.js").ProjectionLike} destination The desired projection.
   */
  transform(source, destination) {
    source = getProjection(source);
    const pixelExtent = source.getExtent();
    const projectedExtent = source.getWorldExtent();
    const scale = getHeight(projectedExtent) / getHeight(pixelExtent);
    composeTransform(tmpTransform,
      projectedExtent[0], projectedExtent[3],
      scale, -scale, 0,
      0, 0);
    transform2D(this.flatCoordinates_, 0, this.flatCoordinates_.length, 2,
      tmpTransform, this.flatCoordinates_);
  }
}


/**
 * @return {Array<number>|Array<Array<number>>} Ends or endss.
 */
RenderFeature.prototype.getEnds =
RenderFeature.prototype.getEndss = function() {
  return this.ends_;
};


/**
 * @return {Array<number>} Flat coordinates.
 */
RenderFeature.prototype.getFlatCoordinates =
    RenderFeature.prototype.getOrientedFlatCoordinates;


export default RenderFeature;